摘要 :
Low energy electrons scattered in the conduction band of a dielectric solid should behave like Bloch electrons and will interact with perturbations of the atomic lattice, i.e. with phonons. Optical as well as acoustic phonons are ...
展开
Low energy electrons scattered in the conduction band of a dielectric solid should behave like Bloch electrons and will interact with perturbations of the atomic lattice, i.e. with phonons. Optical as well as acoustic phonons are included. Moreover, the inelastic scattering is described by the dielectric energy loss function Im(-1/ε) especially reflecting the excitation of valence band electrons, i.e. secondary electrons (SE). With these collective scattering models we have performed the simulation of electron injection and excited electron relaxation and attenuation in the insulator SiO_2. After secondary electron excitation to a mean initial energy of several eV their energy relaxation occurs within a short time interval of 200 fs to full thermalization. There is a very rapid cooling by impact ionization connected with cascading of electrons at the beginning during the first 20 fs, followed by much slower attenuation due to phonon losses in wide-gap dielectrics and insulators. These attenuation times are connected with SE escape depths, even with and against the direction of an electric field within the nonconductive isolating sample.
收起
摘要 :
Printed electronic (PE) devices that sense and communicate data will become ubiquitous as the Internet of things continues to grow. Devices that are low cost and disposable will revolutionize areas such as smart packaging, but a m...
展开
Printed electronic (PE) devices that sense and communicate data will become ubiquitous as the Internet of things continues to grow. Devices that are low cost and disposable will revolutionize areas such as smart packaging, but a major challenge in this field is the reliance on plastic substrates such as polyethylene terephthalate. Plastics discarded in landfills degrade to form microand nanoplastics that are hazardous to humans, animals, and aquatic systems. Replacing plastics with paper substrates is a greener approach due to the biodegradability, recyclability, low cost, and compatibility with roll-to-roll printing. However, the porous microstructure of paper promotes the wicking of functional inks, which adversely affects printability and electrical performance. Furthermore, truly sustainable PE must support the separation of electronic materials, particularly metallic inks, from the paper substrate at the end of life. This important step is necessary to avoid contamination of recycled paper and/or waste streams and enable the recovery of electronic materials. Here, we describe the use of shellac-a green and sustainable material-as a multifunctional component of green, paper-based PE. Shellac is a cost-effective biopolymer widely used as a protective coating due to its beneficial properties (hardness, UV resistance, and high moisture- and gas-barrier properties); nonetheless, shellac has not been significantly explored in PE. We show that shellac has great potential in green PE by using it to coat paper substrates to create planarized, printable surfaces. At the end of life, shellac acts as a sacrificial layer. Immersing the printed device in methanol dissolves the shellac layer, enabling the separation of PE materials from the paper substrate.
收起
摘要 :
Modern electronic devices are moving toward miniaturization and integration with an emerging focus on wearable electronics. Due to their close contact with the human body, wearable electronics have new requirements including low w...
展开
Modern electronic devices are moving toward miniaturization and integration with an emerging focus on wearable electronics. Due to their close contact with the human body, wearable electronics have new requirements including low weight, small size, and flexibility. Conventional 3D and 2D electronic devices fail to efficiently meet these requirements due to their rigidity and bulkiness. Hence, a new family of 1D fiber-shaped electronic devices including energy-harvesting devices, energy-storage devices, light-emitting devices, and sensing devices has risen to the challenge due to their small diameter, lightweight, flexibility, and weavability into soft textile electronics. The application challenges faced by fiber and textile electronics from single fiber-shaped devices to continuously scalable fabrication, to encapsulation and testing, and to application mode exploration, are discussed. The evolutionary trends of fiber and textile electronics are then summarized. Finally, future directions required to boost their commercialization are highlighted.
收起
摘要 :
Semiconducting single-walled carbon nanotube (SWNT) networks are promising for use as channel materials in field-effect transistors (FETs) in next-generation soft electronics, owing to their high intrinsic carrier mobility, mechan...
展开
Semiconducting single-walled carbon nanotube (SWNT) networks are promising for use as channel materials in field-effect transistors (FETs) in next-generation soft electronics, owing to their high intrinsic carrier mobility, mechanical flexibility, potential for low-cost production, and good processability. In this article, we review the recent progress related to carbon nanotube (CNT) devices in soft electronics by describing the materials and devices, processing methods, and example applications in soft electronic systems. First, solution-processed semiconducting SWNT deposition methods along with doping techniques used to achieve stable complementary metal-oxide-semiconductor devices are discussed. Various strategies for developing highperformance SWNT-based FETs, such as the proper material choices for the gates, dielectrics, and sources/drains of FETs, and methods of improving FET performance, such as hysteresis repression in SWNT-based FETs, are described next. These SWNT-based FETs have been used in flexible, stretchable, and wearable electronic devices to realize functionalities that could not be achieved using conventional silicon-based devices. We conclude this review by discussing the challenges faced by and outlook for CNT-based soft electronics.
收起
摘要 :
Since electron microscopy (EM) first appeared in the 1930s, it has held centre stage as the primary tool for the exploration of biological structure. Yet, with the recent developments of light microscopy techniques that overcome t...
展开
Since electron microscopy (EM) first appeared in the 1930s, it has held centre stage as the primary tool for the exploration of biological structure. Yet, with the recent developments of light microscopy techniques that overcome the limitations imposed by the diffraction boundary, the question arises as to whether the importance of EM in on the wane. This Commentary describes some of the pioneering studies that have shaped our understanding of cell structure. These include the development of cryo-EM techniques that have given researchers the ability to capture images of native structures and at the molecular level. It also describes how a number of recent developments significantly increase the ability of EM to visualise biological systems across a range of length scales, and in 3D, ensuring that EM will remain at the forefront of biology research for the foreseeable future.
收起
摘要 :
Abstract Quantum electronics has significantly evolved over the last decades. Where initially the clear focus was on light–matter interactions, nowadays approaches based on the electron’s wave nature have solidified themselves a...
展开
Abstract Quantum electronics has significantly evolved over the last decades. Where initially the clear focus was on light–matter interactions, nowadays approaches based on the electron’s wave nature have solidified themselves as additional focus areas. This development is largely driven by continuous advances in electron quantum optics, electron based quantum information processing, electronic materials, and nanoelectronic devices and systems. The pace of research in all of these areas is astonishing and is accompanied by substantial theoretical and experimental advancements. What is particularly exciting is the fact that the computational methods, together with broadly available large-scale computing resources, have matured to such a degree so as to be essential enabling technologies themselves. These methods allow to predict, analyze, and design not only individual physical processes but also entire devices and systems, which would otherwise be very challenging or sometimes even out of reach with conventional experimental capabilities. This review is thus a testament to the increasingly towering importance of computational methods for advancing the expanding field of quantum electronics. To that end, computational aspects of a representative selection of recent research in quantum electronics are highlighted where a major focus is on the electron’s wave nature. By categorizing the research into concrete technological applications, researchers and engineers will be able to use this review as a source for inspiration regarding problem-specific computational methods.
收起
摘要 :
It is shown for the first time that electron-electron scattering of slow electrons with an energy of 10-50 eV at the surface of some metals is mainly an event of binary scattering of particles with conserved total momentum and ene...
展开
It is shown for the first time that electron-electron scattering of slow electrons with an energy of 10-50 eV at the surface of some metals is mainly an event of binary scattering of particles with conserved total momentum and energy, while analogous scattering at the surface of a semiconductor (n-Si) and an insulator (MgO) is a multiparticle event. A model is proposed, in which the electron subsystem of a solid is character_ized by short-range order. Each electron is at the center of a spherical cell and surrounded by nearest neigh_bors (electrons) with a coordination number of 12. The overlap of the fields of charges gives rise to a negative potential U_c(r)≈U_c, which is virtually constant along the coordinate and contains spherical cells with a cen_tral field U(r) of individual charges. The value of constant negative potential UU depends on the extent of elec_tron screening, which is high for metals and low for semiconductors and insulators. In metals, scattering gov_erned by the binary mechanism may take place (i.e., scattering of a primary electron in the central field of an electron of the metal); this is ensured by a relatively small value of constant potential Uc. The electron sub_system of the metal behaves as a Fermi gas of weakly interacting quasiparticles. Electron screening in semiconductors and insulators is insignificant, and constant negative potential Uc is an order of magnitude higher than the analogous potential in metals. Slow primary electrons are scattered in the total field of many charges before they reach the central field of an individual electron. The electron subsystem of a semiconductor and an insulator in the excitation range studied here behaves as an ensemble of strongly interacting particles.
收起
摘要 :
Electron reemission following photoelectron recapture due to post-collision interaction has been studied at 0.7 eV the inner-shell photoionization threshold of water molecules, using a multi-electron coincidence method. Electron r...
展开
Electron reemission following photoelectron recapture due to post-collision interaction has been studied at 0.7 eV the inner-shell photoionization threshold of water molecules, using a multi-electron coincidence method. Electron reemissions after single Auger decay occur from O and OH fragments which are produced by the dissociations of high-n Rydberg H_2O ~+ states populated through photoelectron recapture. In addition, electron reemissions after double Auger decay are identified in triple coincidence events, where autoionization lines from O and O~+ fragments are observed.
收起
摘要 :
Research on wearable electronic devices that can be directly integrated into daily textiles or clothes has been explosively grown holding great potential for various practical wearable applications. These wearable electronic devic...
展开
Research on wearable electronic devices that can be directly integrated into daily textiles or clothes has been explosively grown holding great potential for various practical wearable applications. These wearable electronic devices strongly demand 1D electronic devices that are light-weight, weavable, highly flexible, stretchable, and adaptable to comport to frequent deformations during usage in daily life. To this end, the development of 1D electrodes with high stretchability and electrical performance is fundamentally essential. Herein, the recent process of 1D stretchable electrodes for wearable and textile electronics is described, focusing on representative conductive materials, fabrication techniques for 1D stretchable electrodes with high performance, and designs and applications of various 1D stretchable electronic devices. To conclude, discussions are presented regarding limitations and perspectives of current materials and devices in terms of performance and scientific understanding that should be considered for further advances.
收起
摘要 :
We investigate the agyrotropic nature of electron distribution functions and their substructure to illuminate electron dynamics in a previously reported electron diffusion region (EDR) event. In particular, agyrotropy is examined ...
展开
We investigate the agyrotropic nature of electron distribution functions and their substructure to illuminate electron dynamics in a previously reported electron diffusion region (EDR) event. In particular, agyrotropy is examined as a function of energy to reveal detailed finite Larmor radius effects for the first time. It is shown that the previously reported ~66 eV agyrotropic "crescent" population that has been accelerated as a result of reconnection is evanescent in nature because it mixes with a denser, gyrotopic background. Meanwhile, accelerated agyrotropic populations at 250 and 500 eV are more prominent because the background plasma at those energies is more tenuous. Agyrotropy at 250 and 500 eV is also more persistent than at 66 eV because of finite Larmor radius effects; agyrotropy is observed 2.5 ion inertial lengths from the EDR at 500 eV, but only in close proximity to the EDR at 66 eV. We also observe linearly polarized electrostatic waves leading up to and within the EDR. They have wave normal angles near 90°, and their occurrence and intensity correlate with agyrotropy. Within the EDR, they modulate the flux of 500 eV electrons travelling along the current layer. The net electric field intensifies the reconnection current, resulting in a flow of energy from the fields into the plasma.
收起
原文获取